Update docs example of webpack url-loader

Latest versions of `url-loader` default `esModule: true` which outputs a module
object with `default` property for asset imports. This behaviour is different
from Metro which doesn't do that.

This breaks compatibility with a lot of React Native libraries since it's
common to do an inline `require` for assets., so it'd work for Metro, but break
with url-loader.

Close #2040

packages/docs/src/pages/docs/getting-started/multi-platform.md

@@ -107,7 +107,8 @@ const imageLoaderConfiguration = {
   use: {
     loader: 'url-loader',
     options: {
-      name: '[name].[ext]'
+      name: '[name].[ext]',
+      esModule: false,
     }
   }
 };